How to Measure Accommodative Lag 

Thank you!

Thanks Phil!

Yes, indeed! No working distance lens or additional calculation is required.

Any help, please

@@UbuntuOphthalm we're in Australia and got them from a local company (Cyclopean Designs) but we've seen them online for sale via eBay and AliExpress - search 'optical flipper'.

Not necessarily. A high lag means that the person is working harder at near with their distance prescription. Reducing the distance prescription will cause blurred vision, if the prescription has been measured accurately. So, usually a high lag necessitates spectacles which provide a reading add such as progressive addition lenses.

@@MyopiaProfile Thank you so much

Hi Abe, us eye doctors do need to measure your prescription for far and for close, at set distances. This provides standardised information for past and future comparison. We then use this information, along with knowledge about your visual environment and activities, to determine the best prescription and best type of spectacle lenses for you. If you're struggling to make the 'forced choice' options of what we call subjective refraction ('subjective' as we're asking for your feedback), ask if your eye doctor can make an objective measure of your refraction instead. There are a couple of techniques (retinoscopy and autorefraction) which are objective, taking the guesswork away. We use these techniques as a starting place and it might be the finishing place for those who can't tell us otherwise, but for most adults we will also want to ask your opinion about what looks clearer to you.

Hi Rashelle, yes I definitely test both eyes, every time. As for prescribing in the situation you describe, I would want to ensure the dominant eye is comfortable while also trying to provide the amblyopic eye as much support as needed. Typically, for non-strabismic patients who need an add, I would prescribe +0.50 less than the near lag, to allow for comfortable near vision. I'd prescribe more than this, up to the full value of the lag, if we also have to deal with esophoria/tropia. In this case, if the amblyopic eye really needs that extra plus at near, I'd consider giving a +0.75 add (the full lag of the dominant eye).

It appears to be a risk for adults as well, but we don't have a lot of data on it. Here's a summary with links to scientific papers: www.myopiaprofile.com/measuring-near-lag-of-accommodation/

Yes. I understood MEM to be a monocular technique - the patient views the target binocularly, but the lens/flipper is very briefly (

@@barneyandhannah yes you're correct. You can only test one eye at a time, but you can quickly change lenses to avoid adaptation, and test with different powers. Holding the flipper up for longer in this video allows for demonstration of the technique.

Holding up the flippers binocularly has the advantage of providing both eyes with the same demand / blur, even if it is done very quickly. It can help to avoid the patient fixing /accommodating with the non-tested eye which could influence the results.

Ha ha ha she has a PhD and is a leading expert in the field 😅